Characterization of random glass fiber-reinforced polypropylene for processing

Abstract

DSC thermal analysis and multi-channel recording have been used to investigate the processing conditions for fiber-reinforced thermoplastic composites. The process combined the film stacking and intermingled fiber techniques using needle-punching to improve the fiber-matrix distribution. The preheating temperature and mold temperature for fiber-reinforced polypropylene composites were in the ranges of 180 ≈ 200 °C and 60 ≈ 100 °C, respectively. DSC analysis and X-ray methods showed the presence of an a crystalline form for PP and PP/GF with the cooling rate at 10 °C/min. Increasing the cooling rate to 20 °C/min, they revealed the presence of a mixture of the monoclinic a crystalline form and the hexagonal β crystalline form. A multi channel recorder was used to determine the completion of impregnation on multi-layer glass fiber reinforced polypropylene, which could significantly reduce the manufacturing cycle time. The main steps in the processing cycle on the surface of composite or inside the composite were determined. The concept of a processing window with respect to solidification rate and molding pressure is introduced and briefly discussed. The mechanical properties of fiber-reinforced polypropylene composite inside the processing window were better than those outside the processing window and were comparable to GE AZDEL®.